title: Lean body mass of well-nourished women is preserved during lactation.
abstract: To determine whether the lean body mass of well-nourished women was mobilized to support milk protein output during lactation, the body composition of 10 lactating and 10 nonlactating women was examined longitudinally at 6-wk intervals between 6 and 24 wk postpartum and at 52 wk postpartum, and that of 10 nulliparous women was examined at equivalent intervals, by using clinical anthropometry and whole-body potassium counting. Milk production was determined at 6-wk intervals during the period of exclusive breast-feeding (6-24 wk postpartum) by the test-weighing procedure. Milk composition was determined by chemical analysis. Dietary intakes were determined at 6-wk intervals between 6 and 24 wk postpartum from 3-d food records with use of a nutrient database. Lean body mass was maintained in women who exclusively breast-fed their infants during the first 6 mo postpartum while consuming dietary protein in amounts that exceeded those of their nonlactating counterparts by 55%. The high protein intakes were sustained throughout lactation despite a progressive reduction by 32% of milk protein output. Lean body mass was preserved throughout lactation in well-nourished women, suggesting that the metabolic needs of milk protein production were met solely by higher protein intakes of the lactating women.
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Children's Nutrition Research Center, Houston, TX 77030, USA. kmotil@bcm.tmc.edu
authors.forename: K J
authors.initials: KJ
authors.lastname: Motil
authors.forename: H P
authors.initials: HP
authors.lastname: Sheng
authors.forename: B L
authors.initials: BL
authors.lastname: Kertz
authors.forename: C M
authors.initials: CM
authors.lastname: Montandon
authors.forename: K J
authors.initials: KJ
authors.lastname: Ellis
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D006801:Humans; D007774:Lactation / Q000378:metabolism*; D008137:Longitudinal Studies; D008894:Milk Proteins / Q000378:metabolism; D008895:Milk, Human / Q000737:chemistry; D009132:Muscles / Q000502:physiology*; D009752:Nutritional Status; D010298:Parity; D049590:Postpartum Period / Q000378:metabolism
chemical_list: D004044:Dietary Proteins; D008894:Milk Proteins